1. Field
The disclosure relates to eye surgery. More particularly, the disclosure relates to systems and methods for treating glaucoma with a glaucoma drainage device.
2. State of the Art
Co-owned U.S. Pat. Nos. 7,431,709, 7,594,899 and 7,837,644 and U.S. Publication No. 2013/0184631A1 describe an elongate glaucoma drainage device (or shunt) as generally shown in Prior Art FIG. 1, which includes a tube 2 with a lumen 3, a fin 4, a beveled distal tip 5, and a proximal end 6. The lumen 3 extends between the distal tip 5 and the proximal end 6 of the tube 2. The glaucoma drainage device 1 may be coated or impregnated with an antiproliferative drug such as Mitomycin C or 5-Fluoro Uracil.
Referring to Prior Art FIG. 2, the current procedure for inserting the glaucoma drainage device 1 of Prior Art FIG. 1 into the eye (referred to herein as “glaucoma implant surgery”) includes the following steps: 1) anesthetizing the eye by injecting lidocaine and epinephrine under the conjunctiva; 2) incising below the limbus and dissecting a flap posterior with a blunt-tipped scissors; 3) placing three LASIK shields saturated with Mitomycin C (0.2 to 0.4 mg/ml) in the flap for 3 minutes followed by irrigation with saline; 4) forming a radial, shallow scleral pocket, approximately 1 mm wide×1 mm in length into the sclera with a sharp knife; 5) inserting a 25 or 27 gauge needle through the apex of the scleral pocket into the anterior chamber wherein the course of the needle approximately bisects the angle formed between the iris and cornea; 6) threading the glaucoma drainage device 1 through the needle tract with a forceps until the distal end of the device (the end furthest away from the surgeon) enters the anterior chamber of the eye; 7) wedging the fin 4 of the glaucoma drainage device snugly into the scleral pocket; and 8) pulling the conjunctiva and Tenon's capsule over the proximal end 6 of the glaucoma drainage device 1 and suturing the flap closed. The entire procedure typically takes 15 to 25 minutes to perform. After the glaucoma implant surgery, the lumen 3 of the glaucoma drainage device 1 provides a flow path for the drainage of aqueous humor from the anterior chamber of the eye into the scleral pocket in order to control TOP of the eye. The pressure drop between the anterior chamber of the eye and the scleral pocket is dictated primarily the interior diameter of the lumen 3 of the glaucoma drainage device 1. Thus, the interior diameter of the lumen 3 can be varied amongst patients for control of TOP for different patients.
Although the aforementioned glaucoma drainage device and the glaucoma implant surgery function well, there is a need to simplify and expedite the procedure. Interviews with many cataract surgeons have indicated that they will perform the glaucoma implant surgery at the time of cataract surgery if there is no conjunctival dissection, no bleeding, no suturing and if the procedure is reduced to less than 5 minutes. Cataract surgeons treat approximately 3 million eyes per year in the U.S. and approximately 20% of patients have glaucoma. This represents a potential market of 600,000 cases per year, which is sufficiently substantial to satiate cataract surgeons with a glaucoma implant surgical procedure better suited to their requirements.
It is important to know that when cataract surgery is performed, two clear corneal incisions are made in the cornea to allow instrumentation to be inserted into the eye to remove the cataractous lens and subsequently replace the lens with an intraocular lens. Further, the anterior chamber is enlarged with a viscous fluid to enable performing the cataract procedure without damaging the endothelial cells under the cornea. The viscous fluid does not leak through the clear corneal incisions.